First House Protector For Voltage Regulators And The Like - Patent 4063148 by Patents-118

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									' United States Patent [w]
4,063,148
[45] Dec. 13, 1977
[ii]
Fehlmann et al.
[54] FIRST HOUSE PROTECTOR FOR VOLTAGE
REGULATORS AND THE LIKE
OTHER PUBLICATIONS
First House Voltage Protector Supplement to GEA
7534 Pub. May 1970.
First House Voltage Protector GE Brochure, Dec.
1972.
Primary Examiner
[75] Inventors: Hans R, Fehlmann, Lenox; Richard
D. Blackburn, Dalton, both of Mass.
[73] Assignee: General Electric Company
Gerald Goldberg
ABSTRACT
[57]
[21] Appl. No.: 701,521
A control circuit for limiting the output voltage of a
voltage regulator or the like to a safe level for consum¬
ers connected close to the voltage regulator. The output
voltage of the regulator is measured and compared to a
reference. If the voltage exceeds the preset level then
the circuit is energized to prevent further tap change
that would increase the voltage output. A time delay is
provided to prevent immediate de-energization of the
circuit when the voltage drops below the preset level.
Should line fluctuations cause further voltage increase,
then the circuit will cause a tap change so as to reduce
the output voltage. If the output voltage drops below a
preset level then the circuit will prevent further tap
changing which would cause any further lowering of
the output voltage.
[22] Filed:
July 1, 1976
[51]	Int. C1.2
[52]	U.S. CI.
	G05F 1/64
323/43.5 S; 361/89;
361/90; 361/187
323/43.5 R, 43.5 S;
[58] Field of Search
317/36 TD, 49, 50, DIG. 5, 141 S; 361/89, 90,
187
[56]
References Cited
U.S. PATENT DOCUMENTS
2,713,142
3,128,424
3,784,846
3,906,248
7/1955	Sealey	
4/1964	Cooley et al.
1/1974	Krick et al.
9/1975	Vieira	
323/43.5 R
323/43.5 R
317/36 TD
317/141 S
1 Claim, 2 Drawing Figures
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U.S. Patent Dec. 13,1977
4,063,148
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U.S. Patent Dec. 13,1977
4,063,148
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1
BRIEF DESCRIPTION OF DRAWING
first house protector for voltage
REGULATORS AND THE LIKE
BACKGROUND OF THE INVENTION
FIG. 1 is a block diagram of one form of control
circuit according to this invention; and
FIG. 2 is a schematic diagram of a preferred form of
voltage regulating control circuit according to this
invention.
5
This invention relates to voltage regulators and the
like, and more particularly, to a control circuit to pre¬
vent excessive high- or low-voltage outputs from such
regulator.
As is well known to those skilled in the electrical 1°
utility field, voltage regulators and other load tap
changing equipment are used in distribution circuits to
compensate for voltage drops along the distribution line
and to assure proper voltage at a distant load center.
However, during high load periods the consumers who 15 Parts throughout,
are closest to the regulator experience higher than rated ^IG. 1 shows a block diagram of the preferred con-
voltages. As is well known, some electrical equipment tro c'rcult generally indicated at 10. Control circuit 10
such as television receivers are impaired by exposure to 1fludeis the regulator output circuit 12 which is fed
higher than rated voltages. Thus, it is desirable to pro- ^ through avoltagesensmg amplifier circuit "to voltage
vide control means in conjunction with voltage regulat- 20 dlvlders 16 and 18 The outPut voltaSe of dlvlders 16
ing equipment to prevent overvoltage conditions on
consumers who are closest to the regulating equipment.
Also, it is well understood that low voltage levels
also has a harmful effect on other types of electrical
equipment; thus, it is further desirable to provide con¬
trol means in conjunction with voltage regulating
equipment that will prevent such equipment from low¬
ering the output voltage below the desired limit for
DESCRIPTION OF PREFERRED EMPODIMENT
This invention relates to a control circuit for voltage
regulating equipment, often referred to as a first house
protector. The preferred form of control circuit accord¬
ing to this invention is shown in the figures of the draw¬
ings in which like numerals are used to indicate like
and 18 is compared with reference voltage signals from
circuit 20 in the sensing amplifiers 22, 24 and 26 as
shown. If the voltage exceeds a preset upper limit relay
28 is energized through amplifier 22 to prevent the
25 regulator tap changing mechanism 30 from initiating
further changes in the raise direction.
If, due to source voltage variations, or load changes,
the output voltage should increase a fixed percent
above the preset upper limit then relay 32 is energized
30 by amplifier 24. When relay 32 is energized it activates
the tap changing mechanism 30 to lower the regulator
output voltage. Should the regulator output voltage
drop below a preset minimum voltage level then ampli¬
fier 26 will energize block lower relay 34. When block
35 lower relay 34 is energized it will operate to prevent the
. .	.	tap changing mechanism 30 from initiating any changes
Briefly, in a preferred form, this mvention comprises to lower the output voltage of the regulator.
a control circuit for voltage regulating equipment to	pjQ 2 shows a schematic diagram of the present
prevent undesired high- or low-voltage settings of the	preferred control circuit 10. As shown a regulator out-
regulator. The control circuit comprises three limit 4q	put 12 is reduced by control transformer 36 and recti-
devices to control the regulator. The first or upper limit	fied and filtered through rectifier bridge 38 and capaci-
comprises a potentiometer that can be preset to an	tors 40 and 42. This rectified voltage indicated by the
upper voltage limit. If the output of the regulator in-	open arrow + DC 1 is the supply voltage for relays 28,
creases over such preset limits, then the upper limit	321 and 34 as is shown by the open arrows + DC 28, +
circuit will be actuated to prevent the tap changer drive 45	DC 32, and + DC 34. The voltage developed
motor from initiating further changes in the raise direc-	zener diode 44 indicated as + DC 2, is used as the DC
tion. If the output drops below the preset level, then the	suppiy voltage for amplifiers 22, 24, 26, and 46 as is
upper limit control circuit will be deactivated, after a	shown by the solid arrows + DC 22, + DC 24, + DC
preset time delay. The second, or run back circuit, pro-	26, and + DC 46. It also provides a supply voltage for
vides means to cause the tap changer drive motor to 50	transistor 48 as shown by solid arrow + DC 48. The
reduce the voltage output should the output voltage	temperature stable reference zener diode 50 develops a
increase beyond the preset upper limit due to any condi-	voltage through trimmer potentiometer 52 which is
tion, such as an increase in source voltage to the regula-	used as a reference signal by amplifiers 22, 24, and 26 as
tor. The third or lower limit circuit includes a potenti-	js shown.
ometer preset at a lower voltage limit. If the output 55	The output voltage 12 is also reduced by means of tap
voltage drops below such preset lower limit then the	54 on the primary of control transformer 36. This volt-
circuit is actuated to prevent the tap changer drive	age is rectified and filtered by rectifier 56, resistor 58,
motor from initiating tap changes which would lower	and capacitor 60 and 62. It is then fed to the operational
the regulator output.	amplifier 46. The output voltage of amplifier 46 which
The invention which is sought to be protected will be 60	directly follows the input voltage, is fed to the voltage
particularly pointed out and distinctly claimed in the	divider circuits 16 and 18. Voltage divider 16 includes
claims appended hereto. However, it is believed that	trimmer potentiometer 64 and level adjustment potenti-
this invention and the manner in which its various ob-	ometer 66. As will be apparent, potentiometer 66 pro¬
jects and advantages are obtained as well as other ob-	vides the upper limit voltage setting which is applied to
jects and advantages thereof, will be better understood 65	the upper limit operating amplifier 22. Through resis-
by reference to the following detailed description of a	tors 68 and 70 the desired percent increase voltage sig-
preferred embodiment particularly when considered in	nal is applied to the lower operating amplifier 24. Volt-
the light of the accompanying drawings.	age divider 18 includes the trimmer potentiometer 72
consumers.
It is, therefore, a principal object of this invention to
provide a control circuit for voltage regulating equip¬
ment to prevent excessive high- or low-voltage outputs
from such equipment.
SUMMARY OF THE INVENTION
across
4,063,148
3
4
and the level adjustment potentiometer 74. As will be
apparent from the circuit the potentiometer 74 provides
the setting for the lower limit voltage which is applied
to the lower limit operating amplifier 26.
The operation of the control circuit will now be de- 5 sent preferred embodiment of this invention it will of
scribed, still referring to FIG. 2. If the output voltage of
the regulator exceeds the upper limit set by potentiome¬
ter 66, then the voltage at the positive input terminal of
amplifier 22 will be higher than the reference voltage
turn off when the output of transistors 76, 80, and 82 to
assure their turn off when the output of their respective
amplifiers is low.
While there has been shown and described the pre-
course be apparent to those skilled in the art that vari¬
ous changes may be made in the circuitry disclosed
without departing from the invention. The spirit and
t	scope of the invention includes all such changes as may
supplied to the other terminal of amplifier 22. Under 10 fau within the invention as defined in the appended
these conditions amplifier 22 turns on and its output
drives transistor 48. Transistor 48 turns on transistor 76.
claims.
What is claimed as new and which it is desired to be
secured by Letters Patent of the United States is:
1. A control circuit for limiting the output of voltage
regulating equipment, such equipment including a drive
means, said control circuit comprising:
a.	means for sensing the output of voltage regulating
equipment;
b.	a first voltage divider fed by said sensing means;
1. said first voltage divider having means for set¬
ting a desired upper limit of the output,
c.	first operating means actuated by an overvoltage
from said setting means of said first voltage divider;
d.	first relay means, said first relay means energized
by said operating means to block further operation
of the drive of the voltage regulating equipment in
a direction to increase the voltage output of the
voltage regulating equipment and;
e.	time delay means connected to said first operating
means to prevent immediate de-energization of said
first relay means when said divider voltage drops
below said preset limit;
f.	a second operating means, said second operating
means actuated by a further overvoltage from said
first voltage divider, said second operating means
energizing a second relay,
1. said second relay effective to cause the drive
means of the voltage regulating equipment to
drive the voltage regulating equipment to reduce
the output voltage,
g.	a second voltage divider, said second voltage di¬
vider having means for setting a desired lower limit
of the output;
h.	third operating means actuated by an undervoltage
from said setting means of said second voltage
divider;
i.	and a third relay means energized by said third
operating means to block further operation of the
drive means of the voltage regulating equipment in
a direction to lower the voltage output of the volt-
Transistor 76 will energize the relay 28. Relay 28 will
open a contact in the regulator tap changing mechanism
30 to prevent operation which would raise the regulator i 5
output. While energization of relay 28 occurs without
any time delay, a time delay is provided to prevent
dropout of relay 28 due to line transient or the like. As
can be seen in FIG. 2, capacitor 78 is charged up during
an operation amplifier 22, and transistors 48 and 76. If 20
the upper limit signal drops below the preset upper
limit, amplifier 22 acts to turn off transistor 48. How¬
ever, capacitor 78 will slowly discharge continuing
transistor 48 in the conducting state. After approxi¬
mately a 10-second delay, capacitor 78 will be suffi- 25
ciently discharged to turn off transistor 48 and thus,
transistor 76, thereby de-energizing relay 28.
If voltage variations from load changes should occur
to increase the output voltage approximately 1 percent
over the present upper limit, then amplifier 24 is turned 30
on. Amplifier 24 will turn on transistor 80 which will
energize the relay 32. Transistor 80 also turns off tran¬
sistor 76 and de-energizes relay 28. Relay 32 operates a
contact in the tap changing mechanism 30 causing the
motor to drive in a direction to lower the voltage out- 35
put. This action continues until the voltage level is low
enough to turn off amplifier 24. Amplifier 24 will turn
off transistor 80 allowing transistor 76 to again turn on
and energize the blocking relay 28.
If the voltage output drops below the preset level of 40
potentiometer 74 then amplifier 26 will be turned on.
Amplifier 26 will turn on the transistor 82 which will
energize the lower blocking relay 34. Relay 34 is pro¬
vided with a contact in the tap changing mechanism 30
which will prevent the motor from driving the mecha- 45
nism in a direction to lower the output voltage.
In the preferred embodiment shown, light-emitting
diodes 84, 86, and 88 are connected across relays 28, 32,
and 34 respectively. These light-emitting diodes 84, 86,
and 88 provide an indicating light for the operation of 50
their respective relays. Also, a diode 90 is provided
connected to the circuit common as indicated which
biases each of transistors 76, 80, and 82 to assure their
age regulating equipment.
* ♦ * * *
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